Image-capturing lens assembly

Abstract

This invention provides an image-capturing lens assembly comprising, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface; a second lens element with negative refractive power; a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface, the object-side and image-side surfaces thereof being aspheric; a fourth lens element with negative refractive power having a concave image-side surface on which at least one inflection point is formed, the object-side and image-side surfaces thereof being aspheric; and a stop disposed between an imaged object and the first lens element; wherein there are four lens elements with refractive power. Such an arrangement of optical elements can effectively reduce the size of the lens assembly, mitigate the sensitivity of the optical system and enable the lens assembly to obtain a higher resolution.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 098138556 filed in Taiwan, R.O.C. on Nov. 13, 2009, the entire contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to an image-capturing lens assembly, and more particularly, to a compact image-capturing lens assembly used in a mobile phone camera.[0004]2. Description of the Prior Art[0005]In recent years, with the popularity of mobile phone cameras, the demand for compact imaging lenses is increasing, and the sensor of a general photographing camera is none other than CCD (charge coupled device) or CMOS (Complementary Metal Oxide Semiconductor Sensor). Furthermore, as advanced semiconductor manufacturing technology has allowed the pixel size of sensors to be reduced and electronic devices have become more compact and powerful, there is an inc...

AI Technical Summary

Benefits of technology

The present invention provides an image-capturing lens assembly comprising four lens elements with refractive power arranged in a specific order. The first lens element has a convex object-side surface and a concave image-side surface, the second lens element has a concave image-side surface, the third lens element has a concave object-side surface and a convex image-side surface, and the fourth lens element has a concave image-side surface. The refractive index of the first lens element is N1, the refractive index of the second lens element is N2, the thickness of the second lens element is CT2, the thickness of the third lens element is CT3, the refractive index of the third lens element is N3, the refractive index of the fourth lens element is N4, the radius of curvature of the object-side surface of the first lens element is R1, the distance between the stop and the image-plane is SL, and the total track length of the lens assembly is f. The invention provides a compact image-capturing lens assembly with improved image quality and reduced sensitivity.

Problems solved by technology

However, the three-element lens has become insufficient for a high-end imaging lens module due to the reduction in the pixel size of sensors and the increasing demand for lens assemblies featuring better image quality.

Such an arrangement of optical elements, however, has the following disadvantages: (1) the freedom of the system is curtailed due to the employment of excess number of spherical glass lenses, thus the total track length of the system cannot be reduced easily; (2) the process of adhering the glass lenses together is complicated, posing difficulties in manufacture.

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